The War Against Malaria: When Will It End?
As the mosquito-borne disease malaria increases in South Korea, fear of it is growing within the country. Earlier this year, in March, the Korea Disease Control and Prevention Agency (KDCA) issued a nationwide malaria alert after genes for the malaria parasite were identified in a mosquito in the Paju area. According to the KDCA, a total of 509 cases have been reported so far this year—nearly a fourfold increase compared to the 193 cases reported in the first seven months of last year.
The lifting of pandemic restrictions and record heat waves on top of the rainy season created excellent conditions for mosquito larvae to thrive in Korea, which may have contributed to the increased spread of malaria. Two hundred cases are expected to arise before the end of the year.
But how exactly does malaria spread? The fact that it is carried by mosquitoes is well known. Malaria is caused by a parasite that commonly infects a certain type of mosquito called the Anopheles mosquito. Anopheles mosquitoes that have fed on infected blood are the only ones that can transmit malaria. It is most prevalent in Africa and parts of Oceania and is sometimes fatal, affecting a total of 247 million people in 2021.
Recently, however, potential solutions for the disease have been emerging. The fight against malaria is not new—scientists have been experimenting with a wide range of methods, including radiation and genetic modification, in order to deal with the disease. One relatively popular idea is the complete eradication of malaria through the use of gene drives.
Gene drive technology allows a select set of genes to modify an animal’s biology in some way. For example, an animal could be made to produce sterile offspring. This trait would be copied through generations so that the inability to reproduce would spread, effectively influencing an entire population. When applied to malaria, there are various approaches to take. The Target Malaria Project and the University of California Malaria Initiative are two different projects that use the same technology in different ways.
Target Malaria, a research consortium funded by the Bill & Melinda Gates Foundation, is a project “aiming to reduce the population of malaria-transmitting mosquitoes in sub-Saharan Africa.” According to its website, the way it plans to use gene drive technology is to “produce genetically modified Anopheles gambiae mosquitoes that will be able to pass on a genetic modification so the modification is established throughout the specific population relatively quickly and is effectively ‘self-sustaining.’” The reduction of female Anopheles mosquitoes is the project’s main objective, as that specific type of mosquito is the one that transmits malaria when it bites a human. To do this, the researchers are inserting genes that produce enzymes called nucleases into the mosquito population, which target specific sequences of DNA. This includes fertility genes or sex-determination genes that will influence reproduction, and by extension, population size. Ultimately, Target Malaria aims to use gene drive technology to eradicate or at least reduce the Anopheles mosquito population.
While the purpose and intention of the project are certainly optimistic, several problems have been pointed out that can result from the eradication of a population, including the impact on the ecosystem. The mosquitoes being targeted are not currently the only food source for any other animal, and the Anopheles species is just one out of 3,500. But the premise itself is worrying for many, as taking a population out of an ecosystem is nothing to overlook. If just one thing goes wrong and predators start to turn their attention to other species to make up for the mosquitoes, unforeseen consequences could arise, destabilizing the delicate natural ecosystem.
The University of California’s approach is similar in the use of gene drive technology to spread a trait rapidly through a population, but it differs in one major aspect: instead of eradicating the Anopheles mosquito population, it modifies it. The main idea is to release a small colony of mosquitoes that have been genetically modified into the wild that would then mate with wild mosquitoes. And with the help of gene drive technology, in just a few generations, every member of the Anopheles population in a specific area could be rendered effectively immune to the malaria parasite. This is supposedly less risky than the Target Malaria project, as it does not wipe out an entire population and instead opts to modify it instead.
Of course, neither approach is perfect. Even within the University of California project, researchers assume that natural evolution and genetics will lead to the species eventually overcoming the gene drive. And for both cases, public opinion is still wary of the potential ramifications of meddling with nature. However, the possibility in itself—the knowledge that if we wanted to, we just might be able to eradicate malaria in a matter of months—is there, and is a testament to the development of technology. Just knowing that we have the option is proof enough that we may soon be able to rid the world of malaria and its fatalities.